If you use the protected-mode (graphical) version of ScanDisk to perform a thorough scan (which includes a surface scan) on an integrated device electronics (IDE) hard disk that is larger than 32 gigabytes (GB) in size, ScanDisk may report errors on every cluster after approximately cluster number 967,393.

This problem may occur on computers that use a Phoenix BIOS and use the Phoenix BitShift translation algorithm to report the geometry of large IDE hard disks. On such computers, the Windows protected-mode IDE disk driver (Esdi_506.pdr) may not correctly recognize the translation mode for the drive, resulting in an inability to access areas of the drive beyond the first 32 GB.

This problem does not occur if the BIOS uses logical block addressing (LBA) Assist translation instead of Phoenix BitShift translation.

A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that are experiencing this specific problem.

To resolve this problem immediately, download the fix by clicking the download link later in this article or contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:

NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

The English-language version of this fix should have the following file attributes or later:

If you have upgraded from another version of Windows and chose to save your previous version of Windows during the upgrade, you will be unable to uninstall back to your previous version of Windows with this update installed.

Disabling the option to uninstall Windows ensures that your system continues to support your large IDE drive.

Important Notes About Upgrading from Windows 98 to Windows 98 Second Edition

When you install this fix on Windows 98 (original edition), the Windows 98 Second Edition version of the fix and a migration DLL are copied to your system as well. If you later upgrade to Windows 98 Second Edition, the Windows 98 Second Edition version of the fix is automatically installed during the upgrade process. This ensures that you do not lose the functionality provided by this fix by upgrading to Windows 98 Second Edition.

For this automatic migration to occur, you must run Windows 98 Second Edition Setup while running Windows 98. If you boot to a command prompt, and run Windows 98 Second Edition Setup in MS-DOS mode, the Windows 98 Second Edition fix is not migrated automatically, and you will be vulnerable to the problem described in the "Symptoms" section until you reinstall the fix.

IMPORTANT: There is no fix available for any version of Windows 95. The reason for this is explained in the following article in the Microsoft Knowledge Base: